JP2001258042A - Display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a display device using a cathode-ray tube that can fully suppress color smear and realize considerably high image quality. SOLUTION: The display device consists of a cathode-ray tube, having a color selection electrode 20 fixed to a frame 21 with a tension added thereto and having an internal magnetic shield 12, that magnetically shields an electron beam and of a degaussing coil placed to the funnel of the cathode-ray tube. The degaussing coil consists of a couple of 1st and 2nd degaussing coils 16a and 16b, placed vertically, and the 1st and 2nd degaussing coils have parallel parts 16a-1 and 16b-1 extended in parallel along the upper side or lower side of the color selection electrode and sneak-path crossing parts 16a-2 and 16b-2, that take a sneak path from both ends of the parallel parts toward an inner side face from the ridges of the funnel and where the respective coils cross.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a cathode ray tube (hereinafter, referred to as a cathode ray tube).
CRT. ), Particularly a display device such as a television.

[0002]

2. Description of the Related Art Generally, in a CRT, an electron beam emitted from an electron beam emitting means such as an electron gun passes through a pore of a color selection electrode and lands on a phosphor.
Emit red, green, or blue light.

Hereinafter, a display device including a conventional CRT, for example, a color television will be described with reference to FIGS. 9 to 12. Each figure shows only those structures that are deeply related to changes in the trajectory of the electron beam due to the external magnetic field of the color television. Referring to FIG. 9, a conventional color television has a color selection electrode structure including a color selection electrode 20 and a frame 21 between a display panel 10 having a phosphor screen and an electron gun 13.
In addition, the color television includes an external magnetic shield structure 18 including the color selection electrode structure and the internal magnetic shield 12. Further, the color television includes a funnel 14 joined to the display panel 10 so as to cover the electron gun 13 and the external magnetic shield structure 18, an explosion-proof band 15, and a degaussing coil 16 disposed on the funnel 14. .

FIG. 10 is a side view of the conventional display device shown in FIG. 9, in which the color selection electrode 20, the angle 21a, and the upper and lower inner magnetic shields 12 which are housed inside the CRT and cannot be normally viewed. FIG. 3 is a side view illustrating a positional relationship between a degaussing coil 16 and an external magnetic field shield structure 18 with a projection position shown in a side view of the display device.

[0005] As shown in FIG. 11, a typical example of a color selection electrode structure including a color selection electrode 20 and a frame 21 is a shadow mask structure 11a. The shadow mask structure 11a is one in which a color selection electrode 20 having a large number of pores formed therein is curved into a predetermined shape by pressing and fixed to a frame 21 by welding. When trying to flatten the screen of a CRT, it is necessary to make this shadow mask (color selection electrode) close to flat. However, the amount of deformation due to thermal expansion of the shadow mask caused by the temperature rise due to the collision of the electron beam is the shadow. It increases as the mask approaches the flat surface, and the positional relationship with the phosphor may be shifted to impair its function.

As a solution to this, as shown in FIG.
As a color selection electrode structure, there has been proposed a method using a so-called tension mask structure 11b in which the color selection electrode 20 having a large number of pores is fixed to the frame 21 in a state where tension is applied only in the vertical direction of the screen. According to this method, the tension mask structure 11 in a state where tension is applied is provided.
b absorbs the elongation of thermal expansion caused by the collision of the electron beam and prevents deformation.

However, when an external magnetic field such as terrestrial magnetism is received while the electron beam reaches the fluorescent screen of the display panel 10 from the electron gun 13, the electron beam receives Lorentz force, and its trajectory changes, and the original landing changes. A part or all of the beam spot lands on a point deviated from the point and hits a phosphor different from the phosphor that should originally emit light, causing a so-called color shift.

In order to suppress the color shift, an internal magnetic shield 12 is provided, and an external magnetic field shield structure 18 is constituted by the internal magnetic shield 12 and a color selection electrode assembly. The deviation is suppressed.

The external magnetic field shield structure is, for example, 36% N
Angle 21a as first frame made of i-Fe material
And a tension mask structure 11b composed of, for example, a second frame arm 21b made of 42% Ni-Fe material and a color selection electrode 20 made of 36% Ni-Fe material, for example, and an interior made of Fe material, for example. Magnetic shield 1
2

Further, a degauss operation is performed to improve the magnetic shielding effect. The degauss operation means that when the external magnetic field shield structure 18 including the color selection electrode structure such as the tension mask structure 11b is considered as a magnetic circuit, the external magnetic field shield structure 18 is subjected to an attenuated alternating magnetic field in the presence of a bias magnetic field, that is, geomagnetism. Is applied by passing an attenuated alternating current through the first degaussing coil 16a and the second degaussing coil 16b.

An approximately quadrangular first degaussing coil 16a of the degaussing coil passes above the color selection electrode 20, passes through a corner above the color selection electrode 20, reaches a funnel, and follows an electron gun along the funnel 14. The funnel 14 on the opposite side via the lower side near the neck 19 surrounding the
Along the upper corner of the color selection electrode 20,
It is connected above the color selection electrode 20. In addition, the substantially quadrangular second degaussing coil 16b passes under the explosion-proof band 15,
The funnel passes through the lower corner of the color selection electrode 20 to the funnel, passes along the ridge of the funnel 14, passes under the vicinity of the neck 19 surrounding the electron gun 13, and follows the ridge of the funnel 14 on the opposite side. Through the lower corner of the explosion-proof band 15 and to the lower part of the explosion-proof band 15. First degaussing coil 16a and second degaussing coil 16b
Is composed of a single connected coil,
And is connected to a power supply circuit, and its magnetomotive force is about 1000 to 4000 AT.

Here, the "ridge line" of the funnel 14 refers to a ridge line from the corner of the rectangular display panel to the neck of the funnel. In this case, the ridge line may not be clear because the funnel cross section becomes circular as approaching the neck side, but it is assumed that the ridge line extends from the corner of the rectangular display panel.

In this degauss operation, since the terrestrial magnetism is applied as a bias magnetic field, after the degauss operation, the external magnetic field shield structure including the tension mask structure 11b is moved in the direction of the terrestrial magnetism, which is the bias magnetic field, as compared with the case where only the terrestrial magnetism is used. Large magnetization occurs. Due to the magnetization generated in the direction of the terrestrial magnetism, a magnetic field for canceling the terrestrial magnetism is generated inside the external magnetic field shield structure. As a result, a magnetic shielding effect is exhibited, a change in the trajectory of the electron beam due to an external magnetic field can be suppressed, and a color shift can be suppressed. Therefore, by increasing the magnetic flux flowing through the external magnetic field shield structure including the tension mask structure 11b out of the magnetic flux generated by the demagnetizing coil, it is possible to generate sufficient magnetization to cancel the geomagnetism after the degauss operation, and It is important to reduce the influence of geomagnetism.

[0014]

However, in the tension mask structure 11b as described above, the color selection electrode 2 is not provided.
Frame 21 which applies tension to the color selection electrode 2
And an arm 21 as a second frame supporting the angle 21a.
Therefore, there is a portion without a geomagnetic shield in the side direction due to the structure. Therefore, arm 2
The horizontal magnetic field component of terrestrial magnetism, which is an external magnetic field in the side direction of 1b and the tube axis direction of the CRT, is not sufficiently shielded.
Further, since the color selection electrode 20 is supported in a state where tension is applied, the magnetic permeability is reduced due to magnetostriction. Further, the magnetic flux generated by the conventional demagnetizing coil arranged in a vertically asymmetrical eight-shape during the degauss operation flows into the tension mask structure 11b having a small magnetic permeability unevenly, and a part of the magnetic flux generated from the demagnetizing coil is reduced. In some cases, it did not effectively flow into the tension mask structure 11b.

The demagnetizing coil of the conventional example shown in FIG. 9 is set on a 25-inch CRT, and the magnitude of the magnetization in the color selection electrode 20 after the degauss operation is numerically analyzed in detail in the second embodiment. As a result, after the degauss operation by the conventional degaussing coil 16,
FIG. 5 (a) shows the magnetization generated in FIG. As shown in FIG. 5A, since the magnetization in the color selection electrode 20 is not sufficient, the horizontal magnetic field component of the terrestrial magnetism is not sufficiently shielded. Therefore, there is a problem that the change in the trajectory of the electron beam due to the horizontal magnetic field component cannot be sufficiently suppressed, and color shift occurs.

Therefore, in view of the above problems, the present invention enhances the magnetic shielding effect by sufficiently magnetizing the color selection electrode by the degauss operation, and can sufficiently suppress the color misregistration as compared with the related art.
It is an object of the present invention to provide a display device capable of achieving extremely high image quality.

[0017]

The above object can be attained by the following present invention.

That is, the display device of the present invention comprises a cathode ray tube having a color selection electrode fixed to a frame under tension, an internal magnetic shield for magnetically shielding an electron beam, and a funnel of the cathode ray tube. A degaussing coil, wherein the degaussing coil comprises a pair of upper and lower first and second degaussing coils, and the first and second degaussing coils are respectively provided with the color selection electrode. A parallel portion extending in parallel along the upper side or the lower side of the funnel, and a wraparound crossing portion that wraps from both ends of the parallel portion to the side surface inside the ridge line of the funnel and crosses each other. Is a display device.

Here, at the time of the degauss operation, the demagnetizing coil is used as a magnetic flux generation source, and the external magnetic field shield structure including the tension mask, the frame, and the internal magnetic shield is considered as a magnetic circuit. In this case, as described above, the first demagnetizing coil and the second demagnetizing coil wrap around the side surface inside the ridge line of the funnel and cross each other,
In other words, by providing a portion that goes around the center of the side surface from the ridge line, not along the ridge line of the funnel, and intersects with each other, it is possible to reduce the magnetic flux leakage from the upper and lower degaussing coils, The magnetic flux flowing parallel to the internal magnetic shield increases because the cross section of the demagnetizing coil perpendicular to the internal magnetic shield increases, and the magnetic flux leaks to the side by crossing each other. The magnetic flux can be reduced. As a result, of the magnetic flux generated between the upper and lower demagnetizing coils, the magnetic flux flowing through the magnetic circuit increases, and the magnetic flux flowing through the tension mask structure increases, so that the demagnetizing magnetic field is effectively applied to the external magnetic field shield structure including the tension mask structure. Applied.

Here, the "linkage surface" of the degaussing coil refers to a curved surface of which the magnetic flux component penetrating the curved surface is composed only of a perpendicular component of the curved surface, out of the curved surfaces having the degaussing coil as an outer periphery. The side surface shape of the degaussing coil in the side view explanatory diagram of (a) corresponds to the shape seen from the side where the outer circumference of the interlinking surface overlaps.

For this reason, after the degauss operation performed in the presence of the terrestrial magnetism as the bias magnetic field, the external magnetic field shield structure including the tension mask structure generates a larger magnetization in the direction of the terrestrial magnetism as the bias magnetic field than before. A magnetic field for canceling geomagnetism is generated inside the external magnetic field shield structure. As a result, the magnetic shielding effect is increased, the change in the trajectory of the electron beam due to the external magnetic field in the horizontal direction is sufficiently suppressed, and the color shift can be sufficiently suppressed.

Further, in the display device according to the present invention, each of the first degaussing coil and the second degaussing coil has a flat cross section at both ends of the parallel portion. Device.

As described above, by forming the cross sections of both ends of the parallel portion extending in parallel along the upper side or the lower side of the color selection electrode to be flat, the mounting of the degaussing coil is simplified, and the degaussing coil is simplified. Can be prevented from shifting.
Furthermore, after the degauss operation, the external magnetic field shield structure including the tension mask structure generates a sufficiently large magnetization to cancel the terrestrial magnetism, the magnetic shielding effect increases, and the change in the trajectory of the electron beam due to the horizontal external magnetic field is sufficiently increased. Color shift can be suppressed sufficiently.

Further, in the display device of the present invention, the explosion-proof band provided has a relative magnetic permeability of 2,000 to 15,000, and the first degaussing coil and the second
The display device is characterized in that the degaussing coil includes a portion disposed on the explosion-proof band at each of the parallel portions or the wraparound intersections.

As described above, the explosion-proof band to be provided has a high magnetic permeability having a relative magnetic permeability of 2,000 or more and 15,000 or less, and an explosion-proof band having a high magnetic permeability is formed in a parallel portion or a wraparound intersection of each degaussing coil. By providing the portion disposed on the band, the magnetic circuit including the tension mask structure can further include an explosion-proof band having a high magnetic permeability, so that among the magnetic fluxes generated from the degaussing coil at the time of degauss, the tension mask structure is removed. The demagnetizing magnetic field is effectively applied to the external magnetic field shield structure including the tension mask structure because the magnetic flux flowing through the magnetic circuit including the magnetic field increases. For this reason, after the degauss operation, the external magnetic shield structure including the tension mask structure has a sufficiently large magnetization to cancel the terrestrial magnetism, the magnetic shielding effect increases, and the change in the trajectory of the electron beam due to the external magnetic field in the horizontal direction is sufficient. And color shift can be sufficiently suppressed.

Further, in the display device according to the present invention, the first and second degaussing coils may be provided on the respective left and right side surfaces of the funnel near the color selection electrode at the respective wraparound intersections. The display device according to claim 1, further comprising a portion disposed substantially parallel to the side.

As described above, by providing the left and right side surfaces of the funnel near the tension mask structure extending substantially parallel to the sides of the display panel at the wraparound intersection of the degaussing coil, the magnetic flux generated by the degaussing coil is reduced. Flowing toward the color selection electrode, the demagnetizing magnetic field is effectively applied to the color selection electrode. For this reason, after the degauss operation, a sufficiently large magnetization is generated in the external magnetic field shield structure including the color selection electrode to cancel the terrestrial magnetism, the magnetic shielding effect increases, and the change in the electron beam trajectory due to the external magnetic field in the horizontal direction is sufficient. And color shift can be sufficiently suppressed.

Further, the display device according to the present invention is characterized in that the first degaussing coil and the second degaussing coil are vertically symmetrically arranged.

By arranging the first demagnetizing coil and the second demagnetizing coil vertically symmetrically, the magnetic field generated by the demagnetizing coil is uniformly applied to the external magnetic field shield structure without waste. For this reason, after the degauss operation, a sufficiently large magnetization that cancels the terrestrial magnetism is generated in the external magnetic field shield structure, the magnetic shielding effect is increased, and the change in the trajectory of the electron beam due to the external magnetic field in the horizontal direction is sufficiently suppressed. The displacement can be sufficiently suppressed.

Further, the display device of the present invention is the display device, wherein the first degaussing coil and the second degaussing coil are formed of one coil.

As described above, by forming the first demagnetizing coil and the second demagnetizing coil with one coil, the workability of mounting the demagnetizing coil is improved, and after the degauss operation,
Magnetization large enough to cancel terrestrial magnetism is generated in the external magnetic field shield structure, the magnetic shielding effect is increased, and the change in the trajectory of the electron beam due to the external magnetic field in the horizontal direction is sufficiently suppressed, and the color shift can be sufficiently suppressed.

[0032]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In order to facilitate understanding of the present invention, the present invention will be described below with reference to embodiments. Each figure shows only structures that are deeply related to changes in the trajectory of the electron beam due to the external magnetic field of the color television as the embodiment. The display device is a color television having a CRT.

First Embodiment In FIG. 1, a color television according to a first embodiment includes a display panel 10 having a phosphor screen and an electron beam.
An external magnetic field shield structure 18 composed of a tension mask structure 11b, which is a color selection electrode structure, and an internal magnetic shield 12 is provided between the electron gun 13 and the electron gun 13 that emits light toward zero. A funnel 14 joined to the display panel 10 so as to cover the electron gun 13 and the external magnetic field shield structure 18.
, A neck 19, and a first degaussing coil 16 a and a second degaussing coil 16 b disposed above and below the funnel 14.

The tension mask structure 11b is composed of a color selection electrode 20 and a frame 21 that supports the edge of the color selection electrode 20 with a tension P applied. The frame 21 supports the color selection electrode 20. The first frame 21a
And a second frame 21b supporting the first frame 21a
It is composed of

FIG. 2 (a) shows the display device according to the first embodiment shown in FIG. 1, which is housed inside the CRT and cannot be viewed normally, the color selection electrode 20, the angle 21a, and the upper and lower internal magnets. FIG. 3 is an explanatory side view showing a positional relationship between a degaussing coil 16 and an external magnetic field shield structure 18 with a side projection position of a shield 12 shown in a side view of the display device. FIG. 2B is a rear view showing the disposition state of the degaussing coil.

The edge of the color selection electrode 20 is supported with a tension of about 80 to 160 kg so that the color selection electrode 20 is made almost flat to make the screen of the CRT flat.
Thereby, the elongation of the thermal expansion that increases due to the collision of the electron beam is absorbed, and the deformation of the color selection electrode 20 can be prevented. However, the relative permeability, which was about 500 before the tension was applied, has been reduced to about 200 by the application of the tension, and the magnetic flux is less likely to flow than when supported without tension, canceling the geomagnetism. However, it is hardly magnetized.

The external magnetic field shield structure has, for example, a thickness of 1.
An angle 21a as a first frame made of a 4% 36% Ni-Fe material and, for example, a 1.4% thick 42% N
Arm 21b as a second frame made of i-Fe material
And a color selection electrode structure that is a tension mask structure 11b including a color selection electrode 20 made of 36% Ni—Fe material having a thickness of 0.1 mm, for example, and a thickness of 0.15.
mm of an internal magnetic shield 12 made of an Fe material.

The first degaussing coil 16a of the degaussing coil according to the first embodiment extends from the parallel portion 16a-1 extending in parallel along the upper side of the color selection electrode 20 to the end of the parallel portion. The neck 1 that wraps around the inner side of the ridge line of the funnel 14 and wraps the electron gun 13 from the wraparound intersection 16a-2 that crosses the second degaussing coil.
Via the lower side of the vicinity of 9, on the opposite side, the inner side of the ridgeline of the funnel 14 is turned around, and
A wraparound intersection 16a-3 intersecting with the second degaussing coil
To the parallel portion 16a-1 extending in parallel along the upper side of the display panel 10. First degaussing coil 16
a and the second degaussing coil 16b are arranged vertically symmetrically and are respectively connected to a power supply circuit, and the magnetomotive force is 2300AT.

The shape of the degaussing coil 16 is such that each of the degaussing coils 16a and 16b includes a parallel portion extending substantially parallel along the upper side or the lower side of the color selection electrode 20, and the inner side of the ridge line of the funnel 14. It is only necessary to provide a wraparound crossing portion that crosses each other and crosses each other. The number of crossings may be one or more, and may cross a plurality of times. Each degaussing coil 16a,
The parallel portion extending substantially in parallel along the upper side or the lower side of the display panel 10 of 16b preferably includes a straight line portion.

The electron beam emitted from the electron gun 13 is
The light passes through the pores of the color selection electrode 20 and lands on the phosphor of the display panel 10 to emit any one of red, green, and blue.

The upper and lower degaussing coils 16a and 16b are wrapped around the inner side of the ridge line of the funnel 14, and are provided with wraparound crossing portions that cross each other on the left and right side surfaces of the funnel 14. Leakage magnetic flux can be reduced, and the inclination between the interlinking surface of the degaussing coil 16 and the internal magnetic shield 12 increases.
The internal magnetic shield 12
And the magnetic flux 30 flowing in parallel along. As a result, of the magnetic fluxes generated in the upper and lower degaussing coils 16a and 16b during the degauss operation, the magnetic flux flowing to the external magnetic field shield structure 18 including the tension mask structure increases, and the demagnetizing magnetic field is effectively applied to the tension mask structure 11b. Further, the provision of the crossing portions can reduce the leakage magnetic flux from the upper and lower degaussing coils. For this reason, after the degauss operation, a sufficiently large magnetization that cancels the terrestrial magnetism is generated in the tension mask structure, the magnetic shielding effect is increased, and the change in the trajectory of the electron beam due to the external magnetic field in the horizontal direction is sufficiently suppressed. Can be sufficiently suppressed, and high image quality can be realized.

Here, the first and second degaussing coils 16a,
The first and second demagnetizing portions 16b are turned around the inner side of the ridge line of the funnel 14 and the effect of providing the wraparound crossing portions that cross each other on the left and right side surfaces of the funnel 14 is further clarified. Coil 16
Reference examples in which a and 16b are wrapped around the inner side of the ridge line of the funnel 14 but are not provided with intersections are shown below.

Reference Example As shown in FIGS. 8A and 8B, the first degaussing coil 16a formed in a saddle shape is a parallel portion extending in parallel along the upper side of the color selection electrode 20. The funnel 1 passes through the upper corner of the color selection electrode 20 from one end of 16a-1.
From the wraparound portion 16a-2 wrapping around the side surface direction of the second frame 21b inside the ridge line of No. 4 from the electron gun 13
Frame 2 inside the ridge of the funnel 14 on the opposite side via the upper side near the neck 19 surrounding the
1b, a wrap-around portion 16a-
From No. 3, it passes through the upper corner of the color selection electrode 20 and leads to a parallel portion 16a-1 extending in parallel along the upper side of the color selection electrode 20. The first degaussing coil 16a and the second degaussing coil 16b are vertically symmetrically disposed above or below the color selection electrode 20, near the color selection electrode 20, for example, on the 3 mm neck side of the color selection electrode 20. Are connected to a power supply circuit, and the magnetomotive force is 230
0AT.

An explosion-proof band 15 'having a high magnetic permeability is provided so as to surround the color selection electrode 20, and a part of the first degaussing coil 16a and a part of the second degaussing coil 16b are respectively provided with the explosion-proof band 15' having a high magnetic permeability. Located above

The upper and lower first and second degaussing coils 16a, 1
The demagnetizing coil 16 b is provided on the inner side surface of the funnel 14 on the inner side from the ridge line of the funnel 14, and is provided on the explosion-proof band 15 having high magnetic permeability.
The inclination between the intersecting surface of the demagnetizing coil 16 and the internal magnetic shield 12 increases, and the cross-sectional area of the intersecting surface of the degaussing coil 16 perpendicular to the internal magnetic shield 12 increases. Increase. As a result, a large amount of magnetic flux generated from the degaussing coil 16 in the degauss operation flows into the external magnetic field shield structure 18 constituted by the color selection electrode structure and the internal magnetic shield 12. For this reason, the magnetization on the surface of the color selection electrode after degauss is
As shown in FIG. 6, the result of a numerical analysis described later shows that a sufficiently large magnetization is generated, and FIG.
As compared with (a), the magnetic shielding effect is improved in the external magnetic field shielding structure including the color selection electrodes,
Color misregistration is suppressed as compared with the conventional example, and high image quality can be realized.

Second Embodiment A second embodiment of the present invention will be described with reference to FIGS. The display device according to the second embodiment in FIG. 3 and FIG.
An explosion-proof band 15 ′ having a high magnetic permeability is provided so as to surround the color selection electrode 20, and includes a first degaussing coil 16 a and a second degaussing coil 16.
b is an explosion-proof band 15 'having a high magnetic permeability.
It is different from the first embodiment in that it is disposed above. The high magnetic permeability referred to in the present invention means that the relative magnetic permeability is 2,000 or more, which is 1.3 to 10 times that of a conventional explosion-proof band.
It means 5000 or less.

The explosion-proof band having a high magnetic permeability has a width of 5% to 20% of the diagonal dimension of the display panel and is disposed so as to surround the color selection electrode. 25 inch C with diagonal dimension of 635mm
At RT, the explosion-proof band is made of, for example, an Fe material having a width of 55 mm, a thickness of 1.0 mm, and a relative magnetic permeability of about 3000. The panel side end is 30 mm from the color selection electrode 20, and the neck side end is from the color selection electrode 20. It is arranged at 25 mm.

FIG. 8 shows the conventional degaussing coil shown in FIG. 9 and the degaussing coil of the second embodiment (Example 2) shown in FIG.
The demagnetizing coils of the reference example shown in FIG. 3 were set on a 25-inch CRT, and the results of numerical analysis of the magnitude of magnetization in the color selection electrode 20 after the degauss operation were performed. The results are shown in FIGS. As shown in FIG. In the numerical analysis, a non-linear magnetic field analysis is performed by a three-dimensional finite element method in consideration of a hysteresis magnetic characteristic of a magnetic material by a curling model theory, and the analysis region is divided into about 70,000 finite elements.

By performing the degauss operation in the presence of geomagnetism which is a bias magnetic field, after the degauss operation, the color selection electrode 2
A larger magnetization is generated in the direction of the earth magnetic field, which is the bias magnetic field, in the external magnetic field shield structure including zero, and a magnetic field for canceling the earth magnetism is generated inside the external magnetic field shield structure. Therefore, it can be said that the greater the magnetization of the color selection electrode 20 after degauss and the more uniform, the more uniform the geomagnetism can be.

The upper and lower degaussing coils are wrapped around the inner side of the ridge of the funnel to provide wraparound intersections which cross each other on the left and right sides of the funnel, and the high permeability permeability explosion-proof band is provided in the parallel part or the wraparound intersection. By including the portion disposed above, the inclination between the linkage surface of the degaussing coil 16 and the internal magnetic shield 12 increases, and the cross-sectional area of the linkage surface of the degaussing coil 16 perpendicular to the internal magnetic shield 12 is increased. Is increased, the magnetic flux 30 flowing in parallel along the internal magnetic shield 12 increases. Further, by providing the intersection, the leakage magnetic flux generated from the upper and lower degaussing coils can be reduced. As a result, of the magnetic flux generated from the degaussing coil in the degauss operation, the magnetic flux flowing to the external magnetic field shield structure including the tension mask structure increases, and the magnetic flux flowing to the tension mask structure increases. For this reason, as shown in FIG. 5B, after the degauss operation, a sufficiently large magnetization for canceling the geomagnetism is generated in the tension mask structure, and the magnitude of the magnetization in the color selection electrode after the degauss is smaller than that of the conventional example. As shown in FIG. 6A, the magnetic flux is more uniform, and the magnetic flux is more effectively reduced by reducing the leakage flux from the upper and lower degaussing coils than in FIG. And the change in the trajectory of the electron beam due to the external magnetic field in the horizontal direction can be sufficiently suppressed, color shift can be sufficiently suppressed, and high image quality can be realized.

Third Embodiment A third embodiment of the present invention will be described with reference to FIG. In the display device according to the third embodiment in FIG. 7, both end portions of the parallel portions of the first demagnetizing coil and the second degaussing coil disposed in the funnel (portions surrounded by dotted lines in FIG. 7A). Is formed flat (FIG. 7).
(B)) is different from the second embodiment shown in FIG. 3 and FIG.

As shown in FIG. 7B, by flattening the cross section of both ends of the parallel portion of the degaussing coil, the mounting of the degaussing coil can be simplified, and the displacement of the degaussing coil can be prevented. As in the second embodiment, after the degauss operation, a sufficiently large magnetization for canceling the terrestrial magnetism is generated in the tension mask structure, the magnetization of the color selection electrode after the degauss becomes large and uniform, and the magnetic shielding effect increases. The change in the trajectory of the electron beam due to the external magnetic field in the horizontal direction is sufficiently suppressed, and the color shift can be sufficiently suppressed.

In the above description of the present invention, a case has been described in which the present invention is applied to a tension mask type in which a color selection electrode having a large number of pores is fixed to a frame with tension applied only in the vertical direction of the screen. However, the present invention is not limited to this, and a method of fixing a color selection electrode having a large number of pores in a state where tension is applied in both the vertical direction and the horizontal direction of the screen and a method called an aperture grille The present invention can be applied to all methods of fixing the color selection electrode to the frame with tension applied thereto, such as a method of fixing the strip to the frame with tension applied in the vertical direction of the screen, and has the same effect. .

In the case where the screen of the color selection electrode is fixed to the frame in a state where tension is applied in the left and right direction, the arrangement of the degaussing coil may be any one of the left and right with respect to the tube axis from the arrangement of the degaussing coil. In this case, the same effect as the present invention can be obtained.

In the above embodiment, the case of using the color selection electrode made of a Ni—Fe material has been described as an example. However, the present invention is also applicable to a display device using a color selection electrode made of another magnetic material such as an iron material. it can.

In the above embodiment, the case of the explosion-proof band made of Fe material has been described as an example. However, the present invention can be applied to a display device using an explosion-proof band made of another magnetic material such as Ni-Fe material.

In the above embodiment, the case of the internal magnetic shield made of Fe material has been described as an example. However, the present invention can be applied to a display device using an internal magnetic shield made of another magnetic material such as permalloy material.

In the above embodiment, a 25-inch color television has been described as an example. However, the present invention can be applied to other display devices using an inch-size cathode ray tube.

In the above embodiment, a color television was described as an example. However, the present invention is not limited to this.
It can be applied to other display devices using a cathode ray tube, such as a T display monitor.

[0060]

In the display device using the cathode ray tube according to the present invention, the first and second degaussing coils wrap around the inner side of the ridge of the funnel and cross each other on the left and right sides of the funnel. By providing the portion, the leakage magnetic flux from the upper and lower degaussing coils is reduced, and the inclination between the interlinking surface of the degaussing coil and the internal magnetic shield is increased. Since the area becomes large, the magnetic flux flowing in parallel along the internal magnetic shield increases. As a result, of the magnetic flux generated from the demagnetizing coil, the magnetic flux flowing through the external magnetic field shield structure including the tension mask structure increases, and the magnetic flux flowing through the tension mask structure increases, so that the demagnetizing magnetic field is effectively applied to the tension mask structure. You. For this reason, by performing the degauss operation in the presence of the terrestrial magnetism that is the bias magnetic field, after the degauss operation, a larger magnetization is generated in the external magnetic field shield structure including the color selection electrode in the direction of the terrestrial magnetism that is the bias magnetic field, and the A magnetic field for canceling geomagnetism is generated inside the magnetic field shield structure. As a result, the magnetic shielding effect is increased, the change in the trajectory of the electron beam due to the external magnetic field in the horizontal direction is sufficiently suppressed, the color shift can be sufficiently suppressed, and high image quality can be realized.

[Brief description of the drawings]

FIG. 1 is a perspective view illustrating a configuration of a display device according to a first embodiment.

FIGS. 2A and 2B are a side view illustrating a positional relationship between the degaussing coil and the external magnetic field shield structure according to the first embodiment, and a rear view illustrating a disposition state of the degaussing coil.

FIG. 3 is a perspective view illustrating a configuration of a display device according to a second embodiment.

FIG. 4 is an explanatory side view showing a positional relationship between a degaussing coil and an external magnetic field shield structure according to a second embodiment.

FIG. 5 is a magnetization distribution diagram of a color selection electrode by a numerical analysis after a degauss operation using a degaussing coil (a) of a conventional example and a degaussing coil (b) of a second embodiment.

FIG. 6 is a magnetization distribution diagram of a color selection electrode by numerical analysis after a degauss operation by a degaussing coil according to a reference example.

FIG. 7A is a perspective view illustrating a configuration of a display device according to a third embodiment, and FIG. 7B is an enlarged cross-sectional view of both ends of a parallel portion of a degaussing coil.

8A is a side view illustrating the positional relationship between the degaussing coil of the reference example and the external magnetic field shield structure, and FIG. 8B is a rear view illustrating the arrangement of the degaussing coil.

FIG. 9 is a perspective view illustrating a configuration of a conventional display device.

FIG. 10 is an explanatory side view showing a positional relationship between a conventional degaussing coil and an external magnetic field shield structure.

FIG. 11 is a perspective view showing a shadow mask structure in an external magnetic field shield structure of a conventional CRT.

FIG. 12 is a perspective view showing a tension mask structure in an external magnetic field shield structure of a conventional CRT.

[Explanation of symbols]

H _ver Vertical magnetic field _Hew East-west magnetic field H _tube tube axial magnetic field 10 Display panel 11a Shadow mask structure 11b Tension mask structure 12 Internal magnetic shield 13 Electron gun 14 Funnel 15 Explosion-proof band 15 'Explosion-proof band with high permeability 16a First degaussing coil 16a -1 Parallel part 16a-2 Circular part 16a-3 Circular part 16b Second degaussing coil 16b-1 Parallel part 16b-2 Circular part 16b-3 Circular part 17 Electron beam orbit 18 External magnetic field shield structure 19 Neck 20 Color selection electrode 21 Frame 21a Angle 21b Arm 30 Magnetic flux

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiroto Inoue 1006 Kazuma Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. 72) Inventor Kaneyoshi Takaura 1006 Kadoma, Kazuma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Inventor Kaku Uchida 1006 Odaka Kazuma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd. CN05 JA20

Claims (6)

[Claims] 1. A cathode ray tube having a color selection electrode fixed to a frame under tension and an internal magnetic shield for magnetically shielding an electron beam, and a degaussing coil disposed in a funnel of the cathode ray tube The degaussing coil comprises a pair of upper and lower first and second degaussing coils, and the first and second degaussing coils are respectively arranged along an upper side or a lower side of the color selection electrode. It has a parallel portion extending in parallel, and a wraparound crossing portion which extends from both ends of the parallel portion to the side surface inside the ridgeline of the funnel and where the coils cross each other. Display device. 2. The display device according to claim 1, wherein each of the first and second degaussing coils has a flat cross section at both ends of the parallel portion. 3. The explosion-proof band provided has a relative magnetic permeability of 2.
000 or more and 15000 or less, and the first and second degaussing coils each include a portion disposed on the explosion-proof band in the parallel portion or the wraparound intersection. Claim 1 or 2
The display device according to claim 1. 4. The first and second degaussing coils are disposed substantially parallel to the sides of the display panel on the left and right side surfaces of the funnel near the color selection electrodes at the respective wraparound intersections. The display device according to any one of claims 1 to 3, wherein the display device includes: 5. The display device according to claim 1, wherein the first degaussing coil and the second degaussing coil are vertically symmetrically arranged. 6. The display device according to claim 1, wherein the first degaussing coil and the second degaussing coil are formed of a single coil.